Endoprosthesis having struts linked by foot extensions

ABSTRACT

The present invention relates to an endoprosthesis having a plurality of web rings coupled by connectors, which include two or more essentially parallel struts and a foot extension protruding from one of the struts. An endoprosthesis constructed according to the principles of the present invention provides an elevated degree of scaffolding to a body lumen while retaining an acceptable degree of flexibility.

FIELD OF THE INVENTION

The present invention relates to an endoprosthesis having elevatedscaffolding properties while retaining an acceptable degree offlexibility. More particularly, the present invention relates to anendoprosthesis having a plurality of web rings coupled by connectorsthat are composed of essentially parallel struts and that include a footextension protruding from one of the struts.

BACKGROUND OF THE INVENTION

Stents, grafts and a variety of other endoprostheses are well known andused in interventional procedures, such as for treating aneurysms,lining or repairing vessel walls, filtering or controlling fluid flow,and expanding or scaffolding occluded or collapsed vessels. Suchendoprostheses can be delivered and used in virtually any accessiblebody lumen of a human or animal and can be deployed by any of a varietyof recognized means.

An endoprosthesis is typically delivered by a catheter system to adesired location or deployment site inside a body lumen of a vessel orother tubular organ. To facilitate such delivery, the endoprosthesismust be capable of having a particularly small crossing profile to reachthe desired deployment site, which may be difficult to access by thetreating physician through the tortuous pathway of the patient'sanatomy. Therefore, it would be desirable to provide the endoprosthesiswith a sufficient degree of longitudinal flexibility during delivery toallow advancement through the anatomy to the deployed site.

Once deployed, the endoprosthesis should be capable of satisfying avariety of performance characteristics. The endoprosthesis should havesufficient rigidity or outer bias to perform its intended function, suchas opening a lumen or supporting a vessel wall. Similarly, theendoprosthesis should have suitable flexibility along its length whendeployed so that it will not kink or straighten when deployed in acurved vessel. In certain application, the endoprosthesis should providean elevated and consistent degree of scaffolding of the vessel wall andprevent plaque from protruding into the artery, for example during thetreatment of atherosclerosis in the carotid arteries. Therefore, itwould be desirable for the endoprosthesis to provide a substantiallyuniform or otherwise controlled scaffolding of the vessel wall.

One type of endoprosthesis is the stent, which is used for the treatmentof atherosclerotic stenosis in blood vessels. After a patient undergoesa percutaneous transluminal angioplasty or similar interventionalprocedure, a stent may be deployed at the treatment site to maintainpatency of the vessel. The stent is configured to scaffold or supportthe treated blood vessel and may be loaded with a beneficial agent,acting as a delivery platform to reduce restenosis or the like.

Numerous endoprosthesis designs and constructions have been developed toaddress one or more of the performance characteristics summarized above.For example, a variety of stent designs are disclosed in the followingpatents: U.S. Pat. No. 4,580,568 to Gianturco; U.S. Pat. No. 5,102,417to Palmaz; U.S. Pat. No. 5,104,404 to Wolff; U.S. Pat. No. 5,133,732 toWiktor; U.S. Pat. No. 5,292,331 to Boneau; U.S. Pat. No. 5,514,154 toLau et al.; U.S. Pat. No. 5,569,295 to Lam; U.S. Pat. No. 5,707,386 toSchnepp-Pesch et al.; U.S. Pat. No. 5,733,303 to Israel et al.; U.S.Pat. No. 5,755,771 to Penn et al.; U.S. Pat. No. 5,776,161 to Globerman;U.S. Pat. No. 5,895,406 to Gray et al.; U.S. Pat. No. 6,033,434 toBorghi; U.S. Pat. No. 6,099,561 to Alt; U.S. Pat. No. 6,106,548 toRoubin et al.; U.S. Pat. No. 6,113,627 to Jang; U.S. Pat. No. 6,132,460to Thompson; U.S. Pat. No. 6,331,189 to Wolinsky et al.; and U.S. Pat.No. 7,128,756 to Lowe et al., the entireties of which are incorporatedherein by reference.

Certain endoprosthesis structures in the prior art are based on joininga plurality of web rings disposed longitudinally with connectors thatincrease the flexibility of the endoprosthesis by providing preferredbending points. One example of a stent in the prior art is illustratedin FIG. 1, in which a plurality of web rings 10 (shown in a flattenedconfiguration), are joined one to the other by connectors 12. Theindividual web rings 10 are formed by a plurality of web elements 14that are sequentially adjoined at junction bends 16.

While the endoprosthesis of FIG. 1 is shown as having web elements 14 ofrectilinear design, endoprosthesis having web elements of differentdesigns are also known in the art. For example, U.S. Patent ApplicationPublication Nos. 2004/0193250 and 2005/0004651, U.S. Pat. Nos. 6,682,554and 6,602,285, International Patent Publication No. WO 00/13611, andGerman Patent Publication No. 19840645, the entireties of which areincorporated herein by reference, disclose endoprosthesis having webelements each formed by a plurality of segments as illustrated in FIG.2. More particularly, web rings 18 are each formed by a plurality ofcrown-shaped web elements 20 and are joined one to the other byconnectors 22.

Both of the endoprostheses of FIGS. 1 and 2 include connectors 12 and 22that are essentially rectilinear in shape. Therefore, thoseendoprostheses inherently have a limited flexibility and a limitedresistance to compressive or torsional forces, for example, to theforces applied to the endoprosthesis during deployment and afterimplantation. In addition, connectors 12 and 22 offer limitedscaffolding to the lumen walls and, if the number of connectors isincreased to improve scaffolding (for example, by joining each junctionbend in one web ring to a junction bend in a neighboring web ring with aconnector), stent flexibility becomes proportionally decreased.Therefore, it would be desirable to provide the endoprosthesis with anelevated degree of scaffolding of the vessel wall while retaining acertain degree of flexibility.

SUMMARY OF THE INVENTION

The present invention relates to an endoprosthesis having a plurality ofweb rings coupled by connectors, which include two or more essentiallyparallel struts and a foot extension protruding from one of the struts.An endoprosthesis constructed according to the principles of the presentinvention provides an elevated degree of scaffolding to a body lumenwhile retaining an acceptable degree of flexibility.

In one embodiment, the endoprosthesis is configured as a stent definedby a web structure that is expandable from a delivery configuration to adeployed configuration and that is formed by a plurality oflongitudinally adjacent web rings. Each of the web rings is defined byweb elements that are disposed circumferentially around the longitudinalaxis of the stent and that are sequentially adjoined at junction bends.More particularly, a first junction bend in a first web ring isconnected to a second junction bend in a second web ring by a connectorthat includes a pair of struts essentially parallel one to the other anda foot extension joining the first to the second parallel struts.

This foot extension includes a first member that extends from the firststrut and that defines the sole portion of the foot extension, and asecond member that is interposed between the sole portion and the secondstrut and that defines the toe portion of the foot extension. Differentdesigns of the sole and toe portions are within the scope of the presentinvention, for example, the sole portion may be essentially rectilinearin shape and the toe portion essentially arcuate.

In one embodiment, the foot extension couples the first and the secondstruts of the connector to the second junction bend.

In another embodiment, a second foot extension also couples the firstand the second struts of the connector and is aligned circumferentiallywith, but in a direction opposite to, the first foot extension.

In still another embodiment, a second foot extensions couples the firstand the second struts of the connector to the first junction bend.

In still another embodiment, another foot extension protrudes from thefirst junction bend and couples the first web ring to the connector.

In still another embodiment, another foot extension protrudes from thesecond junction bend and couple the second web ring to the connector.

Other foot extensions may protrude from junction bends of the web ringsthat are not coupled to the connector.

The struts of the connector may be rectilinear in shape or havemulti-segment or curved profiles. The struts of the web rings may alsobe rectilinear in shape, or may include a central member and first andsecond end members extending from the central member at an obtuse angleto form a crown shape. In the latter embodiment, the web elements arenested one into the other in the contracted delivery configuration andthe web elements of neighboring web rings may be oriented atapproximately 180 degrees in relation to each other.

The endoprosthesis of the present invention may be configured toself-expand from the contracted delivery configuration to the expandeddeployed configuration, or may be deployed by applying a radial pressureto an interior surface of the endoprosthesis, for example, by inflatinga balloon disposed within the endoprosthesis.

BRIEF DESCRIPTION OF THE DRAWINGS

The drawings constitute a part of this specification and includeexemplary embodiments of the invention, which may be embodied in variousforms. It is to be understood that in some instances various aspects ofthe invention may be shown exaggerated or enlarged to facilitate anunderstanding of the invention.

FIG. 1 illustrates a detail view of the web structure of a firstendoprosthesis in the prior art.

FIG. 2 illustrates a detail view of the web structure of a secondendoprosthesis in the prior art.

FIG. 3 illustrates a connector having struts linked by a foot extensionaccording to a first embodiment of the invention.

FIG. 4 illustrates a detail view of a web ring in a variant of theembodiment of FIG. 3.

FIG. 5 illustrates a connector having struts linked by foot extensionsaccording to a second embodiment of the invention.

FIG. 6 illustrates a connector having struts linked by foot extensionsaccording to a third embodiment of the invention.

DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION

Detailed descriptions of embodiments of the invention are providedherein. It is to be understood, however, that the present invention maybe embodied in various forms. Therefore, the specific details disclosedherein are not to be interpreted as limiting, but rather as arepresentative basis for teaching one skilled in the art how to use thepresent invention in virtually any detailed system, structure or manner.

The present invention relates to an endoprosthesis for delivery within abody lumen that is formed by a plurality of web rings coupled byconnectors, which include two or more essentially parallel struts and afoot extension protruding from one of the struts. Additional footextensions may also protrude from the web rings.

An endoprosthesis constructed according to the principles of the presentinvention provides an elevated degree of scaffolding to a body lumen butretains an acceptable degree of flexibility. The endoprosthesis may beconfigured as a stent, graft, valve, occlusive device, trocar oraneurysm treatment device and may be used for a variety of intralumenalapplications, including vascular, coronary, biliary, esophageal, renal,urological and gastrointestinal. For ease of description and withoutrestrictive intent, an embodiment of the present invention will bedescribed hereinafter with reference to a stent.

FIG. 3 illustrates a connector 24 that connects a first web ring 30 to asecond web ring 32 in a stent and that includes two essentially parallelstruts 26 and 28. While struts 26 and 28 are shown as rectilinear inshape, struts 26 and 28 may each be formed by a plurality of segments toprovide a “V”, “W”, or similar shape, or may be curved. FIG. 3 alsoshows that struts 26 and 28 may connect first and second web rings 30and 32 at points that are longitudinally aligned, providing connectors24 with a direction essentially parallel to the longitudinal axis of thestent after the stent is expanded. In other embodiments, connectors 24may have a transversal direction in relation to the longitudinal axis ofthe stent after expansion, in the manner shown in FIG. 2.

A foot extension 34 couples strut 26 to strut 28 at one end of connector24 and includes a sole portion 36 that continues into a toe portion 38,which is interposed between sole portion 36 and strut 26. Sole portion36 and toe portion 38 may each have a variety of shapes, providing footextension 34 with a variety of configurations. For example, sole portion36 may be essentially rectilinear with curved end connections to struts26 and 28, or have an arcuate shape, while toe portion 38 instead may bearcuate in shape, as shown in FIG. 3, or have a multi-segmented shape.Different possible configurations of the sole and toe portions of a footextension are disclosed in U.S. Pat. No. 7,128,756 to Lowe et al. and inU.S. Patent Application Publication Nos. 2005/0107865 to Clifford etal., 2006/0015173 to Clifford et al., 2006/0142844 to Lowe et al.,2007/0021834 to Young et al., and 2007/0021827 to Lowe et al., theentireties of which are incorporated herein by reference.

As shown in FIG. 3, connector 24 couples a first junction bend 40 onfirst web ring 30 to a second junction bend 42 on second web ring 32.Also as shown in FIG. 3, foot extension 34 may be positioned onconnector 24 to operate as the coupling area between connector 34 andjunction bend 42, causing sole portion 36 and junction bend 42 to beintegrally adjoined.

Connector 24 provides the stent with improved radial strength and alsowith improved scaffolding properties due to the two parallel strutsincluded within connector 24 as compared to stents having connectorswith a single strut; for example, as compared to the stents depicted inFIGS. 1 and 2. Further, the increased stent surface density provided bythe pair of struts 26 and 28 in comparison with single strut connectorsprovides an additional barrier to prevent plaque from protruding intothe artery.

While providing increased scaffolding properties, connector 24 retains alevel of flexibility that is adequate for a variety of angioplastyapplications because foot extension 34 includes areas of flexure 44 and46. Moreover, foot extension 34 provides the stent with a lower risk ofsliding after the stent is crimped on a balloon than a straightconnector, because resistance to sliding increases in proportion to theamount of metal segments disposed circumferentially in relation to metalsegments extending longitudinally.

Both struts 26 and 28 and foot extension 34 are produced from the samematerial, but in one embodiment of the invention, one of the two struts26 or 28 is produced from a durable material while the other strut isproduced from a biodegradable material. For example, strut 26 may beproduced from a metal material such as stainless steel or Nitinol (whenthe stent is self-expanding), while strut 28 may be produced from apolylactic acid (a biodegradable polyester derived from lactic acid).Either or both of struts 26 or 28 may also be coated with a therapeuticmaterial, for example, a restenosis-inhibiting material or animmunosuppressant such as everolimus.

Referring now to FIGS. 3 and 4, a foot extension 48 may also bepositioned in first web ring 30, as shown in FIG. 3, and/or in secondweb ring 32. Foot extension 48 may have the same profile as footextension 34 situated in connector 24 or may have a different profile.For example, as shown in FIG. 4, foot extension 48 may include a soleportion 50 essentially rectilinear in shape and a toe portion 52essentially arcuate in shape, but any of the foot extension profilespreviously described with regard to connector 24 may be used in firstweb ring 30.

It should be noted that foot extensions 48 are not necessarily disposedon first web ring 30 and/or 32 only at the junctions with connectors 24,but may be present also in parts of web rings 30 and/or 32 that are notcoupled to connectors 24. Examples of possible dispositions of footextensions 48 on web rings are disclosed in the above mentioned U.S.Pat. No. 7,128,756 to Lowe et al. and in U.S. Patent ApplicationPublication Nos. 2005/0107865 to Clifford et al., 2006/0015173 toClifford et al., 2006/0142844 to Lowe et al., 2007/0021834 to Young etal., and 2007/0021827 to Lowe et al.

Referring now to FIGS. 5 and 6, other embodiments of the inventioninclude connectors that have a plurality of foot extensions. Moreparticularly, FIG. 5 illustrates an embodiment of the invention, inwhich a connector 54 includes first strut 56 and second strut 58,disposed essentially one parallel to the other, and first foot extension60 and second foot extension 62 disposed one opposite to the other, withfoot extension 60 protruding from strut 56 and foot extension 62protruding from strut 58. This design provides the stent with greaterability to absorb torsional stresses than the design of FIG. 3.

Another embodiment of the invention is illustrated in FIG. 6, in whichconnector 64 includes first strut 60 and second strut 68 disposed oneparallel to the other and also includes first foot extension 70 andsecond foot extensions 72 both protruding from opposite ends of strut66. This design provides the stent with greater ability to absorbbending stresses than the design of FIG. 3.

The embodiments of FIGS. 3-6 are to be considered non-limiting, andother embodiments of the invention may include foot extensions thatprotrude from each of the connectors struts but that are not alignedcircumferentially, or more than two foot extensions disposed ondifferent points of the connector.

In each of the embodiments of FIGS. 5 and 6, foot extensions may also bedisposed on the first and/or second web rings, in the same manner asdescribed with regard to the embodiment of FIG. 3.

The embodiments described hereinbefore have been illustrated with regardto web elements formed by essentially rectilinear struts 70, as shown inFIG. 4, which are sequentially joined either by junction bends 72 or byfoot extensions 48.

It should be noted that the connector of the present invention findsequal applicability in web rings formed by web elements of differentshapes. For example, the web elements may be shaped as the crownsillustrated in FIG. 2, in which each of the web elements is formed by acentral member, disposed essentially parallel to the longitudinal axisof the stent in the contracted delivery configuration, and by a firstand a second end members extending from opposite ends of the centralmember at obtuse angles. Such obtuse angles may be the same ordifferent. The crowns are joined sequentially with junction bends thathave arcuate shapes and, in the contracted delivery configuration, arenested one into the other. The crowns of neighboring web rings may bedisposed in opposite directions, that is, the crowns in one web ring maybe disposed at 180 degrees compared to the crowns of a neighboring webring.

A person skilled in the art will appreciate that web elements of stilldifferent shapes may be employed in constructing the web rings and thatsuch alternative designs all fall within the spirit and scope of thepresent invention.

The web rings of the endoprosthesis may be manufactured from a varietyof biocompatible materials known in the art, including metal and plasticmaterials, and may be deployed at a target vessel using techniques alsoknown in the art, either by inflating a balloon coupled to the catheteror, if the endoprosthesis is manufactured from a shape memory materialsuch as Nitinol (a nickel-titanium alloy), by allowing theendoprosthesis to self-expand until contact with the vessel wall isestablished.

While the invention has been described in connection with the abovedescribed embodiments, it is not intended to limit the scope of theinvention to the particular forms set forth, but on the contrary, it isintended to cover such alternatives, modifications, and equivalents asmay be included within the scope of the invention. Further, the scope ofthe present invention fully encompasses other embodiments that maybecome obvious to those skilled in the art and the scope of the presentinvention is limited only by the appended claims.

1. An endoprosthesis for delivery in a body lumen comprising: a webstructure defining an essentially tubular body expandable from acontracted configuration to an expanded configuration; a plurality oflongitudinally adjacent web rings defining the web structure; and aplurality of sequentially adjoined web elements defining the web rings,the web elements being disposed substantially parallel to a longitudinalaxis of the essentially tubular body when in the contractedconfiguration, pairs of the web elements being sequentially adjoined atjunction bends, wherein a first junction bend in a first web ring isconnected to a second junction bend in a second web ring by a connectorhaving a first and a second struts essentially parallel one to theother, wherein a first foot extension joins the first to the secondstruts, and wherein the first foot extension includes a first memberextending from the first strut and providing the sole portion of thefirst foot extension, and a second member interposed between the soleportion and the second strut and providing the toe portion of the firstfoot extension.
 2. The endoprosthesis of claim 1, wherein the soleportion has an essentially rectilinear shape and the toe portion has anessentially arcuate shape.
 3. The endoprosthesis of claim 1, wherein thefirst foot extension couples the first and the second struts of theconnector to the second junction bend.
 4. The endoprosthesis of claim 3,further comprising a second foot extension joining the first to thesecond struts, wherein the second foot extension is alignedcircumferentially with and disposed in a direction opposite to the firstfoot extension.
 5. The endoprosthesis of claim 3, further comprising asecond foot extensions joining the first to the second parallel struts,wherein the second foot extension couples the first and the secondstruts of the connector to the first junction bend.
 6. Theendoprosthesis of claim 1, further comprising a third foot extensionprotruding from the first junction bend and coupling the first web ringto the connector.
 7. The endoprosthesis of claim 1, further comprising afourth foot extension protruding from the second junction bend andcoupling the second web ring to the connector.
 8. The endoprosthesis ofclaim 6, wherein the first and/or the second web rings comprise footextensions extending from junction bends not coupled to the connector.9. The endoprosthesis of claim 1, wherein the endoprosthesis is a stent.10. The endoprosthesis of claim 1, wherein the first and the secondstruts are rectilinear.
 11. The endoprosthesis of claim 1, wherein thefirst and the second struts have multi-segment or curved profiles. 12.The endoprosthesis of claim 1, wherein the web elements are rectilinearin shape.
 13. The endoprosthesis of claim 1, wherein each of the webelements comprises a central member having a first and a second ends,wherein the central member is disposed essentially parallel to thelongitudinal axis in the contracted configuration, wherein the centralmember is connected at the first end to a first end member at a firstobtuse angle, and wherein the central member is connected at the secondend to a second end member at a second obtuse angle.
 14. Theendoprosthesis of claim 13, wherein the first and the second obtuseangles are essentially equal.
 15. The endoprosthesis of claim 13,wherein the web elements of each web ring are nested one into the otherin the contracted delivery configuration, and wherein the junction bendshave an arcuate shape.
 16. The endoprosthesis of claim 13, wherein theweb elements in the first web ring are oriented at approximately 180degrees in relation to the web elements in the neighboring web ring. 17.The endoprosthesis of claim 1, wherein the web structure is configuredto self-expand from the contracted configuration to the expandedconfiguration.
 18. The endoprosthesis of claim 1, wherein the webstructure is configured to expand from the contracted configuration tothe expanded configuration by application of a radial pressure to aninterior surface of the essentially tubular body.